diff --git a/core/utils/deprecation.js b/core/utils/deprecation.js
index b849c2a1a..a361f563d 100644
--- a/core/utils/deprecation.js
+++ b/core/utils/deprecation.js
@@ -15,7 +15,8 @@
  * @name Blockly.utils.deprecation
  * @namespace
  */
-goog.provide('Blockly.utils.deprecation');
+goog.module('Blockly.utils.deprecation');
+goog.module.declareLegacyNamespace();
 
 
 /**
@@ -29,7 +30,7 @@ goog.provide('Blockly.utils.deprecation');
  *     if any.
  * @package
  */
-Blockly.utils.deprecation.warn = function(
+const warn = function(
     name, deprecationDate, deletionDate, opt_use) {
   let msg = name + ' was deprecated on ' + deprecationDate +
       ' and will be deleted on ' + deletionDate + '.';
@@ -38,3 +39,5 @@ Blockly.utils.deprecation.warn = function(
   }
   console.warn(msg);
 };
+
+exports = {warn};
diff --git a/tests/deps.js b/tests/deps.js
index 45860bd0c..daed787d5 100644
--- a/tests/deps.js
+++ b/tests/deps.js
@@ -172,7 +172,7 @@ goog.addDependency('../../core/utils.js', ['Blockly.utils'], ['Blockly.Msg', 'Bl
 goog.addDependency('../../core/utils/aria.js', ['Blockly.utils.aria'], []);
 goog.addDependency('../../core/utils/colour.js', ['Blockly.utils.colour'], []);
 goog.addDependency('../../core/utils/coordinate.js', ['Blockly.utils.Coordinate'], []);
-goog.addDependency('../../core/utils/deprecation.js', ['Blockly.utils.deprecation'], []);
+goog.addDependency('../../core/utils/deprecation.js', ['Blockly.utils.deprecation'], [], {'lang': 'es6', 'module': 'goog'});
 goog.addDependency('../../core/utils/dom.js', ['Blockly.utils.dom'], ['Blockly.utils.Svg', 'Blockly.utils.userAgent']);
 goog.addDependency('../../core/utils/global.js', ['Blockly.utils.global'], []);
 goog.addDependency('../../core/utils/idgenerator.js', ['Blockly.utils.IdGenerator'], []);